Separation of m-xylene from o-xylene by extractive distillation

Abstract

m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent comprises propoxypropanol; propoxypropanol and 1,4-butanediol; ethyl benzoate and ethylene glycol phenyl ether and benzyl alcohol.

The nature of the present invention having been described and illustrated by examples, what we wish to claim as new and useful and secure by Letters Patent is: 
     
       1. A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of an extractive agent, recovering essentially pure m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot or reboiler, the extractive agent comprises propoxypropanol. 
     
     
       2. The method of claim 1 in which the extractive agent comprises a mixture of propoxypropanol and at least one of the group consisting essentially of: propylene glycol, 1,4-butanediol, 1,5-pentanediol, hexylene glycol, diethylene glycol.